Related art media curling systems include indentation, belt, and/or baffle-type curlers. An indentation curler as shown in FIG. 1A includes a soft roll 105 having an elastomeric surface that deforms under pressure applied by a penetrating roll 115, which is a hard roll that is urgable against the soft roll 105. An indentation-type curler typically requires a large force to be applied by the penetrating roll for deforming the soft roll 105, and media interposing the hard roll 115 and the soft roll 105.
A related art belt-type curler as shown in FIG. 1B includes a belt 107 entrained by one or more belt rolls 110. A penetrating roll 115 is urgable against the belt 107 for deforming media carried by the belt 107. The indentation or belt-type curler may be sufficient for light weight paper. For heavier weight paper, however, a more substantial belt deformation may be necessary to accommodate a desired deformation of media carried by the belt 107, which may lead to premature system failure. Belt tracking issues may be problematic for heavier paper jobs.
A related art baffle-type curler as shown in FIG. 1C includes a first soft outer roll 112, a penetrating roll 115, a second soft outer roll 117, and an idler roll 120. The idler roll 120 and the first outer roll 112 define a nip entrance through which paper is fed through a narrow paper path comprising a baffle and the penetrating roll 115. The penetrating roll 115 is configured to be movable toward the baffle for bending and pushing the paper between the first outer roll 112 and the second outer roll 117, or between a roll and the baffle. The baffle-type curler may be less effective for lighter weight paper, which must be bent to have a smaller radius than is necessary for heavier weight paper. The baffle-type curler also has a configuration that curls paper while leaving larger lead edge and trail edge lengths more unaffected than those of paper curled by other related art curlers.
Moreover, the above-discussed related art curling systems are configured for imparting a curl in a sheet in a single direction. Related art systems are not suitable for imparting a curl in a sheet that extends in either a first direction or a second direction, wherein the first direction is different than, e.g., opposite from the first direction. Similarly, related art systems are not suitable for imparting a plurality of curls in a sheet wherein the at least two of the plurality of curls extend in opposite directions.